The present invention relates to a liquid chromatograph apparatus. More particularly, the invention relates to a liquid chromatograph apparatus arranged so as to determine contents or concentrations of respective components of a sample solution by comparing the sample solution with a reference solution.
In a liquid chromatograph apparatus, an eluent is first introduced into a separation column, passed through a detecting device and then discharged. After passage through the detecting device, the eluent is discharged into open air through a flow passage resisting member. Since a finely particulate ion-exchange resin is packed in the separation column, a high pressure is imposed on the inlet side of the column. In many cases, a differential refractometer or beam absometric photometer is used as the detecting device. A sample cell and a reference cell are disposed in the detecting device. Luminous fluxes are radiated on each of these cells, and transmitted or reflected rays are taken and the solutions in the two cells are compared with respect to the absorbance or refractive index.
The environment is not always identical between the sample cell and the reference cell. More specifically, although the effluent from the separation column is continuously passed to the sample cell, the reference solution in the reference cell is kept stationary in a closed chamber. In general, the reference cell is disposed quite independently from the conduit system where the sample cell is located, and both the ends of the reference cell are closed at the time of measurement. Therefore, the pressure conditions differ between both the cells, and this pressure difference results in a measurement error.
There is known a liquid chromatograph apparatus in which separately from a separation column, a reference column is disposed in parallel to the separation column downstream of a pump so that an effluent from the reference column is continuously fed into the reference cell. In this known apparatus, the sample cell and reference cell are connected to each other in the upstream portions thereof through the two columns, but in the downstream portions, they are independent from each other. In this apparatus, the pressure difference can be moderated to some extent, but it cannot be said that the effect is sufficient. Moreover, since the eluent must be fed continuously to two column passages, the amount consumed of the eluent is twice as large as in the first mentioned liquid chromatograph apparatus, and the structure becomes complicate.